JPH06143310A - Molding method for regenerated urethane molded form - Google Patents

Abstract

PURPOSE:To provide a low-cost method for simply molding a regenerated urethane molded form in which inner pulverized material is not observed from a surface and which has excellent appearance from a waste of urethane RIM molded form. CONSTITUTION:A method for obtaining a regenerated urethane molded form has the steps of mixing urethane base binder in pulverized material of urethane RIM molded form and hot pressing mixture 14 in a specific shape, and comprises the step of adding a black pigment to the binder, wherein particle size of the pulverized material is 0.2mm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a regenerated urethane molded product having a predetermined shape from a crushed product of a urethane RIM molded product.

[0002]

2. Description of the Related Art Urethane RIM molding method (also referred to as reaction injection molding method) is a method in which a polyol component and an isocyanate component are collision-mixed at a high pressure by a high-pressure injection machine, and the mixture is injected into a mold. Although it is used for molding urethane molded products, it is widely used for molding automobile bumpers, mudguards, and other urethane products because the molding time is extremely short.

By the way, when a urethane product is molded by the urethane RIM molding method, the urethane mixed liquid is reactively cured not only in the cavity portion of the mold but also in the gate portion of the mold. And the urethane RIM formed in the gate portion
Since the gate is an unnecessary part, it is cut off and discarded as waste after the product is removed from the mold. In addition, a defective product may be produced during the molding due to an incorrect molding condition, and the defective product is also discarded.

However, when a large amount of urethane products are used in recent years, the amount of the urethane RIM molded product as the above-mentioned waste also becomes large, so that it is necessary to re-use it from the viewpoint of resource saving and waste disposal. Utilization is being considered.

Conventionally, there are the following methods for reusing the waste. First, the waste material of urethane RIM molding is crushed and sieved to a particle size of 2 mm or less. Then, an uncolored urethane binder is mixed with the pulverized product having a particle diameter of 2 mm or less, and the pulverized product is adhered to the prescribed shape by heating and pressing into a prescribed shape to obtain a regenerated urethane molded product. The particle size distribution of the pulverized product sieved to a particle size of 2 mm or less was 0.7 mm in most cases.

However, in the regenerated urethane molded product molded as described above, as shown in the sectional view of FIG. 2, the thickness of the binder layer 20 on the surface is as thin as 20 μ to 50 μ.
The crushed material 22 inside can be seen through. Moreover, since the surface of the urethane RIM product molded by the urethane RIM molding method is coated in various colors, a recycled urethane molded product molded using a crushed product formed from defective products after coating is However, there is a problem that the color of the coating film on the surface of the pulverized product is seen through from the outside as spots, which impairs the product value.

The amount of the binder mixed with the pulverized material is increased to increase the thickness of the binder layer 20 to, for example, 20.
By making the binder layer 2 thick by 0 μm or more
Although it is possible to prevent 0 from becoming transparent, the advantage of using waste is diminished because the product price increases due to the increase in the amount of binder used.

[0008]

Therefore, the present invention provides a method for easily and inexpensively molding a recycled urethane molded product having a good appearance in which a crushed product inside is not seen through from the surface, from a waste product of the urethane RIM molded product. To do.

[0009]

[Means for Solving the Problems]

The present invention is a method for obtaining a regenerated urethane molded product by mixing a urethane-based binder with a crushed product of a urethane RIM molded product and heating and pressing the mixture into a predetermined shape. The present invention relates to a method for molding a recycled urethane molded article, which is characterized in that it has a thickness of 0.2 mm or less and a black pigment is added to the urethane binder.

[0011]

As a result of making the particle size of the crushed product as small as 0.2 mm or less, the surface of each crushed product visible through the binder layer on the surface of the regenerated urethane molded product, that is, the spots are reduced. Further, as a result of adding a black pigment to the binder that binds the pulverized product, the binder layer on the surface of the regenerated molded product becomes black and the light transmittance is lowered, and the pulverized product inside is less likely to be seen through from the outside of the regenerated molded product. . Due to their synergistic effect, the pulverized material inside the regenerated molded article is not seen through from the outside at all, and the regenerated molded article has a good appearance without spots.

[0012]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a sectional view of a press die showing a state before heating and pressing in an embodiment of the present invention. First, the pulverized product of the urethane RIM molded product, the urethane-based binder, and the press mold used in the present invention will be described.

As the crushed product of the urethane RIM molded product, defective products of various urethane RIM molded products, or crushed products such as unnecessary gates generated during the molding are used. The crushing is performed by a known crushing means such as a grinder. The pulverized product has a particle size of 0.2 mm or less, preferably 0.2 mm to 0.05 mm, which is collected by sieving with a sieve or the like. The surface of the urethane RIM molded product, which is the base of the pulverized product, may be painted in an appropriate color.

The urethane binder is preferably a known one-pack type of a prepolymer having a terminal NCO formed by the reaction of a polyol and a diisocyanate. This one-pack type urethane binder has the property of reacting with moisture in the air to cure, and the reaction is accelerated by heating. The polyol used for the one-component urethane binder is preferably a polyether type or a polyester type having a viscosity of 8000 to 12000 cps, and the diisocyanate is preferably crude MDI. The ratio of the polyol and the diisocyanate is determined depending on the type of the polyol and the diisocyanate used, and is not constant. Examples of usable urethane binders include Sampren BD-1 (manufactured by Sanyo Kasei) and the like.

A black pigment is added to the urethane binder. The black pigment used is a paste in which carbon black is mixed with a plasticizer such as dioctyl phthalate (DOP). The amount of carbon black in the black pigment varies depending on the type of carbon black and the like, but normally, when the total amount of the black pigment (the sum of the plasticizer and the carbon black) is 100% by weight, 10 to 4% of that amount
The amount of 0% by weight is preferable from the viewpoint of color and ease of dispersion in the urethane binder. The amount of the black pigment added to the urethane-based binder is set to about 1/2 to 4/3 of the weight of the binder (not including the black pigment) so that the adhesive strength of the binder is not impaired and the binder is sufficiently added. It is preferable in that it can be colored.

The press die 10 is pressurizable by a press device (not shown), and has a product-shaped cavity inside the die. Further, it is adapted to be heated by a heating device (not shown). The heating device is a press die 1.
A heater or the like may be provided inside 0, a hot air heater or the like may be provided outside the press die, or any other known device may be used.

Next, a method of molding the regenerated urethane molded article of the present invention using the pulverized product, urethane type binder and the like will be described. First, the urethane RIM molded product having a particle size of 0.2 mm or less is mixed with the urethane binder to which the black pigment is added to form a mixture 14 of the crushed product and the binder.

Then, the mixture 14 is heated and pressed into the mold 1.
0 cavity 12 is filled. And usually 100
While heating to ˜180 ° C., hot pressing is performed at a pressure of about 60 to 150 kg / cm ² . As a result, the binder is cured by reaction, the pulverized material is adhered integrally, and the shape of the crushed material is fixed in the shape of a cavity to form a regenerated urethane molded product.
At this time, the binder not only bonds the pulverized material, but also forms a layer and hardens at the portion in contact with the inner surface of the cavity. Therefore, the obtained regenerated molded article is one whose surface is covered with the black binder layer, and the pulverized material inside is not seen through from the outside. Then, the heating press is stopped, the press die 10 is opened, and the regenerated molded product is taken out.

One embodiment of the present invention will be described below by showing the pulverized product, urethane binder, black pigment and the like used. As the pulverized product, a defective urethane RIM bumper with a white surface and a particle size of 0.2 mm or less obtained by pulverizing the gate part were used. Samprene BD-5 (isocyanate content 11%, viscosity 6000-8000 cp, Sanyo Kasei) was used as the urethane-based binder. As a black pigment, DOP80
A mixture of 20% by weight of carbon black (trade name: RM-7689, manufactured by Dainippon Ink and Chemicals, Inc.) in% by weight was used.

Then, a binder mixture obtained by adding 10% by weight of the black pigment to 10% by weight of the urethane-based binder and 80% by weight of a pulverized product are mixed, and the mixture with the pulverized product is filled in the press die 10 to obtain 150 ℃ and 100kg
By heat-pressing at / cm ² , an automobile mudguard (mudguard) as a urethane recycled molded product was molded.

The resulting mudguard had a black binder layer on the surface, and had a good appearance in which the pulverized material inside was concealed by the black binder layer on the surface.

[0022]

As described above, according to the present invention, a recycled molded product having a good appearance can be obtained from a waste product of the urethane RIM molded product. Moreover, since a large amount of binder is not required, it can be molded at low cost. Furthermore, even a painted urethane RIM molded product can be crushed and used, so that it has an excellent effect in terms of reuse of waste and environmental protection.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a press die showing a state before hot pressing according to an embodiment of the present invention.

FIG. 2 is a sectional view of a recycled urethane molded product obtained by a conventional method.

[Explanation of symbols]

 10 Press type 12 Cavity 14 Mixture

Claims (1)

[Claims] 1. A method for obtaining a regenerated urethane molded product by mixing a urethane-based binder with a crushed product of a urethane RIM molded product and heating and pressing the mixture into a predetermined shape, wherein the crushed product has a particle size of 0.2 mm or less. And a black pigment added to the urethane-based binder.